1. Field of the Invention
The present invention relates to an abnormality prediction system for secondary batteries that predicts an abnormality in secondary batteries.
Priority is claimed on Japanese Patent Application No. 2009-224225, filed Sep. 29, 2009, the contents of which are incorporated herein by reference.
2. Description of the Related Art
As one of the techniques of determining an abnormality in secondary batteries, a technique is utilized in which a parameter value, such as a voltage or a temperature, indicative of a state of each secondary battery is measured and the battery whose parameter value is over a threshold value is determined to be abnormal.
In addition, to avoid a decrease in performance of an assembled battery due to variance in performance of a plurality of secondary batteries that constitute the assembled battery, there is proposed a technique of calculating their average voltage and adjusting variations in cell voltage (for example, Japanese Laid-Open Patent Publication, No. 2006-136070 (hereinafter, referred to as Patent Document 1)).
The techniques as described above improve performance and reliability of a secondary battery or the assembled battery in which a plurality of secondary batteries are used. Here, in such techniques, if an abnormality has occurred in one of the secondary batteries, the abnormality of the secondary battery is notified to a user (the equipment/system driven by the batteries, and its user). Conventionally, an abnormality of a secondary battery is notified to the user after the secondary battery is detected to be in an abnormal state. Therefore, if there is an unexpected bait or the like of the equipment/system due to an occurrence of the abnormality in a battery, there is a possibility of a large loss in merit for the user (for example, although required be operated at the present moment, the battery system becomes inoperable, or other cases). Therefore, there is a demand for a technique of predicting a secondary battery that can be in an abnormal state as early as possible before it becomes actually in an abnormal state, to thereby avoid the aforementioned event as much as possible.
Therefore, the present invention has an object to provide an abnormality prediction system for secondary batteries, capable of predicting a secondary battery that is likely to fall into the abnormal state before the secondary battery falls into the abnormal state.